The invention is directed to modified polymers with increased drug-loading including compounds of formula (I): wherein Z is a poly(lactic-co-glycolic acid) (PLGA) polymer having molecular weight from 1-15 kDa and where the ratio of lactide to glycolide in the PLGA polymer is from 1:10 to 10:1 formula (II) R1 are independently H, R2, OH, O-alkyl, —O—R2, NH—R2, -linker-R2, or -and R2 are independently one or more therapeutic agents. The invention is also directed to nanoparticle drug delivery systems including a PLGA-b-PEG block copolymer and a stabilizer and to drug delivery systems including PLGA-b-PEG block copolymer polyvinyl alcohol (PVA) nanoparticle and the modified polymer substantially as described herein.
